Lord Elgin Thin Thin A
It has a NOS dial, a NOS Elgin crown, and a NOS JB Champion center expansion band. It is about as close as I will ever get to a NOS Thin Thin. According to Diveboy’s database, it is the Thin Thin A.
One minor thing I’ve notice about his case design, #9815, is that it comes in two variations. One version has brushing all the way around the side of the bezel and like this one, there is only brushing between the lugs, and the rest of it is polished.